Help with muffins

I have a catering event coming up next month and they are wanting a selection of muffins. I did this one other time for them and I was disappointed with my muffins. They did not crown very well. Instead of a tall crown they spread out on top of the pan. I tried several things. baking at higher temps, thicker batter, different pans, but ALL of my muffins did the same thing. Any suggestions to making a muffin with a tall crown? thanks!